# All files / src/providers/deepseek Streaming.ts

89.74% Statements 70/78
81.25% Branches 52/64
100% Functions 3/3
95.71% Lines 67/70

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     import { ChatRequest, ChatChunk } from "../Provider.js";
    import { APIError } from "../../errors/index.js";
    import { logger } from "../../utils/logger.js";
    import { mapSystemMessages } from "../utils.js";
    import { fetchWithTimeout } from "../../utils/fetch.js";

    export class DeepSeekStreaming {
      constructor(
        private readonly baseUrl: string,
        private readonly apiKey: string
      ) {}

      async *execute(request: ChatRequest, controller?: AbortController): AsyncGenerator<ChatChunk> {
        const abortController = controller || new AbortController();
        const {
          model,
          messages,
          tools,
          max_tokens,
          response_format,
          thinking: _thinking,
          headers: _headers,
          requestTimeout,
          ...rest
        } = request;

        const mappedMessages = mapSystemMessages(messages, false);

        const body: Record<string, unknown> = {
          model,
          messages: mappedMessages,
          stream: true,
          ...rest
        };

        if (max_tokens) body.max_tokens = max_tokens;
        Iif (tools && tools.length > 0) body.tools = tools;
        Iif (response_format) body.response_format = response_format;

        let done = false;
        // Track tool calls being built across chunks
        const toolCallsMap = new Map<
          number,
          { id: string; type: string; function: { name: string; arguments: string } }
        >();

        try {
          const url = `${this.baseUrl}/chat/completions`;
          logger.logRequest("DeepSeek", "POST", url, body);

          const response = await fetchWithTimeout(
            url,
            {
              method: "POST",
              headers: {
                Authorization: `Bearer ${this.apiKey}`,
                "Content-Type": "application/json",
                ...request.headers
              },
              body: JSON.stringify(body),
              signal: abortController.signal
            },
            requestTimeout
          );

          if (!response.ok) {
            const errorText = await response.text();
            throw new Error(`DeepSeek API error: ${response.status} - ${errorText}`);
          }

          logger.debug("DeepSeek streaming started", {
            status: response.status,
            statusText: response.statusText
          });

          if (!response.body) {
            throw new Error("No response body for streaming");
          }

          const reader = response.body.getReader();
          const decoder = new TextDecoder();
          let buffer = "";

          while (true) {
            const { value, done: readerDone } = await reader.read();
            Iif (readerDone) break;

            const chunk = decoder.decode(value, { stream: true });
            buffer += chunk;

            const lines = buffer.split("\n\n");
            buffer = lines.pop() || "";

            for (const line of lines) {
              let trimmed = line.trim();

              // Handle carriage returns
              Iif (trimmed.endsWith("\r")) {
                trimmed = trimmed.substring(0, trimmed.length - 1);
              }

              Iif (!trimmed.startsWith("data: ")) continue;

              const data = trimmed.replace("data: ", "").trim();
              if (data === "[DONE]") {
                done = true;

                // Yield final tool calls if any were accumulated
                if (toolCallsMap.size > 0) {
                  const toolCalls = Array.from(toolCallsMap.values()).map((tc) => ({
                    id: tc.id,
                    type: "function" as const,
                    function: {
                      name: tc.function.name,
                      arguments: tc.function.arguments
                    }
                  }));
                  yield { content: "", tool_calls: toolCalls, done: true };
                }

                return;
              }

              try {
                const json = JSON.parse(data);

                // Check for errors in the data
                if (json.error) {
                  throw new APIError("DeepSeek", response.status, json.error.message || "Stream error");
                }

                const delta = json.choices?.[0]?.delta;
                const deltaContent = delta?.content;
                const deltaReasoning = delta?.reasoning_content;

                if (deltaContent || deltaReasoning) {
                  yield {
                    content: deltaContent || "",
                    reasoning: deltaReasoning || "",
                    thinking: deltaReasoning ? { text: deltaReasoning } : undefined
                  };
                }

                // Handle tool calls delta
                if (delta?.tool_calls) {
                  for (const toolCallDelta of delta.tool_calls) {
                    const index = toolCallDelta.index;

                    if (!toolCallsMap.has(index)) {
                      toolCallsMap.set(index, {
                        id: toolCallDelta.id || "",
                        type: "function",
                        function: {
                          name: toolCallDelta.function?.name || "",
                          arguments: toolCallDelta.function?.arguments || ""
                        }
                      });
                    } else {
                      const existing = toolCallsMap.get(index)!;
                      Iif (toolCallDelta.id) existing.id = toolCallDelta.id;
                      Iif (toolCallDelta.function?.name) {
                        existing.function.name += toolCallDelta.function.name;
                      }
                      Eif (toolCallDelta.function?.arguments) {
                        existing.function.arguments += toolCallDelta.function.arguments;
                      }
                    }
                  }
                }
              } catch (e) {
                // Re-throw APIError
                if (e instanceof APIError) throw e;
                // Ignore other parse errors
              }
            }
          }
          done = true;
        } catch (e) {
          // Graceful exit on abort
          if (e instanceof Error && e.name === "AbortError") {
            return;
          }
          throw e;
        } finally {
          // Cleanup: abort if user breaks early
          if (!done) {
            abortController.abort();
          }
        }
      }
    }